Method and apparatus for laser induced thermo-acoustical streaming of liquid

Abstract

A laser induced thermo-acoustical system has a waveguide for propagating laser radiation to an absorbing layer of a tip. The tip has an absorbing layer serving to absorb the laser radiation propagating through the waveguide. The absorbing layer has such an absorption coefficient that upon absorbing the laser radiation the absorbing layer heats up to boil a quantity of a liquid when the tip is surrounded by the liquid. A laser induced thermo-acoustical method calls for providing a waveguide for propagating laser radiation to the absorbing layer of the tip to be at least partially absorbed by the absorbing layer and to boil a quantity of the liquid surrounding the tip and generating the stream of liquid. The laser induced thermo-acoustical streaming of the liquid is used, in particular, for the treatment of a root canal and periodontal pockets.

What is claimed is: 
     
       1. A laser radiation induced thermo-acoustical method of generating a stream of a liquid, the method comprising:
 providing a laser source and a tip, the tip comprising a waveguide and an absorbing layer surrounded by a liquid; 
 propagating laser radiation from the laser source through the waveguide to the absorbing layer; 
 heating the absorbing layer in response to the absorbing layer absorbing a portion of the laser radiation; and 
 boiling the liquid surrounding the absorbing layer, in response to heating the absorbing layer, to generate bubbles of vapor of the liquid and to generate acoustical pressure to generate the stream of the liquid, 
 wherein the absorbing layer of the tip has an absorption coefficient that allows boiling of the liquid. 
 
     
     
       2. The method of  claim 1 , wherein the laser radiation has a pulse width selected from a range of 0.001 ms to 100 ms, a repetition rate selected from a range of 1 Hz and 10000 Hz, energy per pulse from a range of 5×S J/cm 2  to 500×S J/cm 2 , wherein S is an area of an aperture of the waveguide, a laser power of the laser source is selected from a range of 20 W to 1000 W, and incident fluence on the absorbing layer is selected from a range of 5 J/cm 2  to 500 J/cm 2 . 
     
     
       3. The method of  claim 1 , wherein the laser radiation has a pulse width selected from a range of 0.05 ms to 10 ms, a repetition rate selected from a range of 1 Hz and 100 Hz, energy per pulse from a range of 10×S J/cm 2  to 100×S J/cm 2 , wherein S is an area of an aperture of the waveguide, a laser power of the laser source is selected from a range of 50 W to 250 W, and incident fluence on the absorbing layer is selected from a range of 10 J/cm 2  to 100 J/cm 2 . 
     
     
       4. The method of  claim 1 , wherein the absorption coefficient ranges from 0.5 to 1.0. 
     
     
       5. The method of  claim 1 , wherein the absorption coefficient ranges from 0.8 to 1.0. 
     
     
       6. The method of  claim 1 , wherein a thickness of the absorbing layer ranges from 0.01 mm to 0.5 mm. 
     
     
       7. The method of  claim 1 , wherein a thickness of the absorbing layer ranges from 0.05 mm to 0.2 mm. 
     
     
       8. The method of  claim 1 , wherein the absorbing layer is disposed on a distal end of the tip. 
     
     
       9. The method of  claim 1 , wherein the absorbing layer is disposed on a side of the tip. 
     
     
       10. The method of  claim 1 , wherein the absorption layer has a shape influencing diversion of streaming of the liquid.